I've sent an email to the contact details listed on the site however there hasn't been a response yet. I have attempted to purchase the Addon Google Export component from the site however payment seems to have failed due to an issue with GetExpressCheckoutDetails.
The full error message is;
GetExpressCheckoutDEtails failed: SSL read: error: 00000000:lib(0):funct(0):reason(0), errno 104(56)
Payment was made 2015-05-22 at approximately 00:52 GMT.
Email was sent to firstname.lastname@example.org with additional details.